Water and fluorinated alcohol mediated/promoted tandem insertion/aerobic oxidation/bisindolylation under metal-free conditions: Easy access to bis(indolyl)methanes

A green tandem reaction, including insertion/aerobic oxidation/bisindolylation, starting from indoles and diazo compounds has been developed. The combination of water and fluorinated alcohol plays dual roles as solvent and promoter in this chemical transformation. Molecular oxygen in the air acts as an oxidant. 3,3'-Bis(indolyl)methanes with quaternary carbon were produced under metal-free conditions. No any catalyst and additive were required. N-2 and water were released as sole by-products. Absence of water and fluorinated alcohol resulted in Wolff rearrangement product. (C) 2021 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

The green tandem reaction starting from indoles and diazo compounds utilizes water and fluorinated alcohol as solvent and promoter, respectively, to synthesize 3,3'-bis(indolyl)methanes under metal-free conditions. The sole by-products released are N-2 and water. Absence of water and fluorinated alcohol results in Wolff rearrangement product.